SELECT : This is a DML command in SQL that retrieves data from the database in the form of query results. The command supports the following keywords and clauses :
FROM This keyword specifies the name of the table.
* This keyword selects all the columns of the table.
WHERE This keyword gives the search condition that specifies the data to be retrieved.
AND This operator is used to combine two or more search conditions.
ORDER BY This keyword sorts the query result on one or more columns.
GROUP BY This keyword groups the query result and lets you generate summary result for each group.
NULL values This value indicates that the data is not present.
Subquery This is the query that is place inside the main query. It passes its query result to the main query.
INSERT : This is a DML command in SQL that you use to add data in rows of a table.
SYNTAX : INSERT INTO table-name (column-names) VALUES (constant/NULL)
UPDATE : This is a DML command in SQL that you use to change data on rows of a table.
Syntax : UPDATE table-name SET column-name-value WHERE condition
DELETE : This is a DML command in SQL that removes one or more rows of data from a table.
Syntax : DELETE FROM table-name WHERE condition.